<!DOCTYPE html>
<html>
<body>
<div>
  <a href="tel://181********">拨打电话</a>
</div>
</body>
</html>

<style>
    body{
        width:100%;
        height:auto;
        margin:50px auto;
        text-align:center;
    }
    a{
      font-size:26px;
      font-weight:700;
    }
</style>